Generally, a hybrid electric vehicle is driven by an engine which generates torque from fuel combustion and an electric motor which generates torque from an electric battery or other source of electricity.
The hybrid electric vehicle may be classified into two types depending on a power source, or power path, of the engine and the motor. A parallel type of hybrid electric vehicle is driven by mechanical power of the engine directly and uses electric power of the motor in case such a need arises. On the other hand, a straight type (or a series type) of hybrid electric vehicle is driven by electric power of the motor which is converted from mechanical power of the engine by a generator.
In the parallel hybrid vehicle, in order to transfer power of the engine to a driving shaft, an engine clutch may be mounted between the engine and the motor. The hybrid vehicle may provide an electric vehicle (EV) mode that provides running of the vehicle with a torque of only the motor and a hybrid electric vehicle (HEV) mode that provides running of the vehicle with the combination of an engine torque and a motor torque according to whether the engine clutch is coupled.
The hybrid electric vehicle may advantageously estimate and learn a touch point of the engine clutch for stable power delivery and rapid torque response.
A transmission mounted electric device (TMED) type of the hybrid electric vehicle, which may be provided with an automatic transmission, uses a wet engine clutch and learns the touch point of the engine clutch when a shift stage, position, is a P stage or an N stage.
However, the hybrid electric vehicle which is provided with a dual clutch transmission (DCT) may use a dry engine clutch, so learning of the touch point of the engine clutch is necessary compared to the wet engine clutch. Moreover, a conventional method for learning the touch point of the engine clutch applied to wet engine clutch may be less accurate than desired accuracy.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.